Your questions refer to different videos with different errors.
The processes in the last video can be reproduced as follows:
View: Entire Library>All Tracks, Global Search : Artist Name (Koto)
1. a correctly tagged file (without cover) is copied per Explorer into the album directory.
2. find more from the same Folder(All) and File>Add/Rescan gets the file into the DB.
3. Previous View (Icon bar) jumps back to the view with the search (The new track only appears after F5)
4. All "Find more from (Album, Library,...)" show the new track.
5. Find more from the same Album retrieves an inappropriate artwork from the web and displays it for the album.
6. Properties of one of the old tracks>Artwork>Apply to all..: The saved cover is not transferred. The new file is not edited.
Not shown in the video:
7. Properties of the new file>Artwork: Remove the inapproriate "unsaved image" (from 5.) and check "Apply to all Files of Album/Serie" deletes the correct
Artwork from all tracks of the album.
Later the inappropriate artwork is automatically fetched from the web again and assigned to all
tracks of the album.
8. Look for the the right cover in the web an paste it to the track in the Properties.
9. Restart MM because it refuses to accept pasting
10. Now pasting works and the cover is distibuted to all files of the album.
I cannot imagine that I should always need 10 steps for such an import process.
I mean there are 4 errors:
5. In "My Library" of the Info Panel, no automatic lookup somewhere in the world should happen. (optional?)
6. Distribute should work.
7. Only selected pics should be deleted.
9. Pasting should always work